Turbochargers may be used in an engine system to increase a pressure of air supplied to the engine for combustion. In one example, the turbocharger includes a turbine, coupled in an exhaust passage of the engine, which at least partially drives a compressor via a shaft to increase the intake air pressure. High pressure air from the turbine or the compressor may leak by non-contact labyrinth seals and turbocharger bearings into an oil cavity surrounding the shaft of the turbocharger. Because the low pressure oil cavity is in fluid communication with a crankcase of the engine, crankcase pressure may increase due to the leakage of the high pressure air leading to crankcase over-pressure events and removal of the turbocharger from the engine system.
In other examples, crankcase over-pressure events may occur due to other factors, such as degradation of piston rings, which increase blow-by around the piston, and/or degradation of an evacuation system which maintains a pressure of the crankcase. In such examples, however, the turbocharger may still be removed from the engine system even though it is not the cause of the crankcase over-pressure event, as the exact cause of the crankcase over-pressure event may be unknown.